1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
|
/*
* MIPS idle loop and WAIT instruction support.
*
* Copyright (C) xxxx the Anonymous
* Copyright (C) 1994 - 2006 Ralf Baechle
* Copyright (C) 2003, 2004 Maciej W. Rozycki
* Copyright (C) 2001, 2004, 2011, 2012 MIPS Technologies, Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/export.h>
#include <linux/init.h>
#include <linux/irqflags.h>
#include <linux/printk.h>
#include <linux/sched.h>
#include <asm/cpu.h>
#include <asm/cpu-info.h>
#include <asm/cpu-type.h>
#include <asm/idle.h>
#include <asm/mipsregs.h>
/*
* Not all of the MIPS CPUs have the "wait" instruction available. Moreover,
* the implementation of the "wait" feature differs between CPU families. This
* points to the function that implements CPU specific wait.
* The wait instruction stops the pipeline and reduces the power consumption of
* the CPU very much.
*/
void (*cpu_wait)(void);
EXPORT_SYMBOL(cpu_wait);
static void r3081_wait(void)
{
unsigned long cfg = read_c0_conf();
write_c0_conf(cfg | R30XX_CONF_HALT);
local_irq_enable();
}
static void r39xx_wait(void)
{
if (!need_resched())
write_c0_conf(read_c0_conf() | TX39_CONF_HALT);
local_irq_enable();
}
void r4k_wait(void)
{
local_irq_enable();
__r4k_wait();
}
/*
* This variant is preferable as it allows testing need_resched and going to
* sleep depending on the outcome atomically. Unfortunately the "It is
* implementation-dependent whether the pipeline restarts when a non-enabled
* interrupt is requested" restriction in the MIPS32/MIPS64 architecture makes
* using this version a gamble.
*/
void r4k_wait_irqoff(void)
{
if (!need_resched())
__asm__(
" .set push \n"
" .set arch=r4000 \n"
" wait \n"
" .set pop \n");
local_irq_enable();
}
/*
* The RM7000 variant has to handle erratum 38. The workaround is to not
* have any pending stores when the WAIT instruction is executed.
*/
static void rm7k_wait_irqoff(void)
{
if (!need_resched())
__asm__(
" .set push \n"
" .set arch=r4000 \n"
" .set noat \n"
" mfc0 $1, $12 \n"
" sync \n"
" mtc0 $1, $12 # stalls until W stage \n"
" wait \n"
" mtc0 $1, $12 # stalls until W stage \n"
" .set pop \n");
local_irq_enable();
}
/*
* Au1 'wait' is only useful when the 32kHz counter is used as timer,
* since coreclock (and the cp0 counter) stops upon executing it. Only an
* interrupt can wake it, so they must be enabled before entering idle modes.
*/
static void au1k_wait(void)
{
unsigned long c0status = read_c0_status() | 1; /* irqs on */
__asm__(
" .set arch=r4000 \n"
" cache 0x14, 0(%0) \n"
" cache 0x14, 32(%0) \n"
" sync \n"
" mtc0 %1, $12 \n" /* wr c0status */
" wait \n"
" nop \n"
" nop \n"
" nop \n"
" nop \n"
" .set mips0 \n"
: : "r" (au1k_wait), "r" (c0status));
}
static int __initdata nowait;
static int __init wait_disable(char *s)
{
nowait = 1;
return 1;
}
__setup("nowait", wait_disable);
void __init check_wait(void)
{
struct cpuinfo_mips *c = ¤t_cpu_data;
if (nowait) {
printk("Wait instruction disabled.\n");
return;
}
switch (current_cpu_type()) {
case CPU_R3081:
case CPU_R3081E:
cpu_wait = r3081_wait;
break;
case CPU_TX3927:
cpu_wait = r39xx_wait;
break;
case CPU_R4200:
/* case CPU_R4300: */
case CPU_R4600:
case CPU_R4640:
case CPU_R4650:
case CPU_R4700:
case CPU_R5000:
case CPU_R5500:
case CPU_NEVADA:
case CPU_4KC:
case CPU_4KEC:
case CPU_4KSC:
case CPU_5KC:
case CPU_25KF:
case CPU_PR4450:
case CPU_BMIPS3300:
case CPU_BMIPS4350:
case CPU_BMIPS4380:
case CPU_BMIPS5000:
case CPU_CAVIUM_OCTEON:
case CPU_CAVIUM_OCTEON_PLUS:
case CPU_CAVIUM_OCTEON2:
case CPU_CAVIUM_OCTEON3:
case CPU_JZRISC:
case CPU_LOONGSON1:
case CPU_XLR:
case CPU_XLP:
cpu_wait = r4k_wait;
break;
case CPU_RM7000:
cpu_wait = rm7k_wait_irqoff;
break;
case CPU_PROAPTIV:
case CPU_P5600:
/*
* Incoming Fast Debug Channel (FDC) data during a wait
* instruction causes the wait never to resume, even if an
* interrupt is received. Avoid using wait at all if FDC data is
* likely to be received.
*/
if (IS_ENABLED(CONFIG_MIPS_EJTAG_FDC_TTY))
break;
/* fall through */
case CPU_M14KC:
case CPU_M14KEC:
case CPU_24K:
case CPU_34K:
case CPU_1004K:
case CPU_1074K:
case CPU_INTERAPTIV:
case CPU_M5150:
case CPU_QEMU_GENERIC:
case CPU_I6400:
cpu_wait = r4k_wait;
if (read_c0_config7() & MIPS_CONF7_WII)
cpu_wait = r4k_wait_irqoff;
break;
case CPU_74K:
cpu_wait = r4k_wait;
if ((c->processor_id & 0xff) >= PRID_REV_ENCODE_332(2, 1, 0))
cpu_wait = r4k_wait_irqoff;
break;
case CPU_TX49XX:
cpu_wait = r4k_wait_irqoff;
break;
case CPU_ALCHEMY:
cpu_wait = au1k_wait;
break;
case CPU_20KC:
/*
* WAIT on Rev1.0 has E1, E2, E3 and E16.
* WAIT on Rev2.0 and Rev3.0 has E16.
* Rev3.1 WAIT is nop, why bother
*/
if ((c->processor_id & 0xff) <= 0x64)
break;
/*
* Another rev is incremeting c0_count at a reduced clock
* rate while in WAIT mode. So we basically have the choice
* between using the cp0 timer as clocksource or avoiding
* the WAIT instruction. Until more details are known,
* disable the use of WAIT for 20Kc entirely.
cpu_wait = r4k_wait;
*/
break;
default:
break;
}
}
void arch_cpu_idle(void)
{
if (cpu_wait)
cpu_wait();
else
local_irq_enable();
}
#ifdef CONFIG_CPU_IDLE
int mips_cpuidle_wait_enter(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index)
{
arch_cpu_idle();
return index;
}
#endif
|
